This invention relates generally to steam turbines, and particularly to steam turbine steam inlet and outlet piping that includes portions fabricated from shape memory alloys.
Steam and gas turbines are used, among other purposes, to power electric generators, and gas turbines also are used, among other purposes, to propel aircraft and ships. A steam turbine has a steam path which typically includes, in serial-flow relationship, a steam inlet, a turbine, and a steam outlet. A gas turbine has a gas path which typically includes, in serial-flow relationship, an air intake (or inlet), a compressor, a combustor, a turbine, and a gas outlet (or exhaust nozzle). Compressor and turbine sections include at least one circumferential row of rotating blades. The free ends or tips of the rotating blades are surrounded by a stator casing.
The steam inlet piping is installed at room temperatures when the steam turbine is assembled. During startup and operation, the pipes expand and can exert force and moments on the steam turbine casing. These forces can distort the casing of the steam turbine which can cause rubbing of the internal moving components of the turbine.
In one aspect, a steam turbine is provided that includes a steam inlet pipe coupled to a steam inlet port in a steam turbine housing. At least a portion of the steam inlet pipe is fabricated from at least one of a shape memory alloy having a memorized activated configuration and a negative thermal expansion ceramic having an activated configuration.
In another aspect, a method of controlling forces exerted on a steam turbine by a steam inlet pipe is provided. The steam turbine includes a steam inlet pipe coupled to a steam inlet port in a steam turbine housing. The method includes fabricating at least a portion of the steam inlet pipe from at least one of a shape memory alloy having a memorized activated configuration and a negative thermal expansion ceramic having an activated configuration, installing the steam inlet pipe with the at least a portion of the steam inlet pipe in an initial configuration at a first temperature, and heating the at least a portion of the steam inlet pipe with steam flowing into the steam turbine to a second temperature which reconfigures the at least a portion of the steam inlet pipe to the activated configuration.